A power failure of 200 to 300 ms long occurs when an AC electric rolling stock crosses a switching section. In the control recently performed, main circuit currents are restricted in the vicinity of the switching section by spot detection. This not only deteriorates the riding comfort but also produces an excitation inrush current flowing to a rolling stock main transformer when switching a feeding circuit. In other words, a main transformer equipped in an AC electric rolling stock produces an excitation inrush current unless applying a voltage to an appropriate phase when receiving a supply of power from an overhead wire. The excitation inrush current not only causes unnecessary operations in feed protection devices but also increases the capacity of earth power-supply equipment.
In the technology described in Japanese Patent Application Publication No. 7-117531A, on the other hand, section switching equipment performs optimum phase angle switching control in order to obtain an optimum closing phase angle of a power supply in the switching section, preventing the occurrence of an excitation inrush current. In Japanese Patent Application Publication No. 2003-291694A, the phase of a middle section of a switching section is controlled by a converter installed in ground equipment in order to switch the middle section to a different power supply feed section.
However, although the technology described in JP7-117531A can prevent the occurrence of an excitation inrush current in the switching section, rolling stock main circuit currents are temporarily restricted when passing through the switching section, deteriorating the riding comfort and causing instant power failure in an auxiliary machine. Moreover, although preventing the occurrence of an excitation inrush current by controlling the closing phase angle by means of the switching section is effective in a feed system using the switching section, it does not serve as a countermeasure in a dead section. For instance, when passing through the dead section or when a rolling stock parked at a storage track attaches a pantograph to an overhead wire to excite a transformer, an excitation inrush current flows into a main transformer.
In JP2003-291694A, on the other hand, placing the converter in the middle section of the switching section results in increasing the size of the equipment.
In the conventional technologies, in case of a power failure of an overhead wire as a result of a power failure of a substation other than when passing through a switching section or dead section, supply of power to various auxiliary machines equipped in a rolling stock is stopped, and there are no countermeasures to such circumstance. Driving the auxiliary machines by means of regenerative energy of the rolling stock at the time of a power failure is considered. In this case, however, the main transformer is reversely excited by the regenerative energy, pressurizing the overhead wire from the pantograph. For this reason, at the time of a power failure of the overhead wire, the pantograph needs to be separated from the overhead wire to perform an operation.
In the case of the dead section other than the switching section system, “overhead dead section indicator” is installed before the dead section, and a driver of the rolling stock is required to visibly confirm this indicator, perform a notch-off operation, and coast through the dead section when passing through the dead section.